This invention relates to a thin-film magnetic head employing a magnetoresistive element.
In a thin-film magnetic head employing a magnetoresistive element (hereinafter referred to as MR element) 1 as shown in FIG. 1, the relationship between the strength of the signal magnetic field Hs and the resistivity variation of the MR element .DELTA..rho. is non-linear on the whole, as shown in FIG. 2, even if spins within the MR element are perfectly ordered in the longitudinal direction. In order to avoid the generation of harmonic distortion in magnetoelectric transducing, a bias magnetic field H.sub.B is supplied so that the operating point is located in linear characteristic region such as a point P.
On the other hand, in case where spins within the MR element are not ordered in a prefered orientation, i.e., a longitudinal direction of the MR element, such as in a magnetically isotropic material in a extremely bad case, the relation between the resistivity variation of the MR element .DELTA..rho. and the magnetic field strength H has quite large hysteresis, as shown in FIG. 3. In such condition the harmonic distortion, especially the second harmonic distortion exhibits a complicated variation with respect to the signal magnetic field. Therefore it is difficult to suppress the generation of the harmonic distortion.
Further it is more important to order the orientations of spins in case where the thin-film magnetic head has a multi-channel construction. Otherwise the respective characteristics of the channels are scattered from each other, as shown in FIG. 4, even if the optimum bias magnetic field is provided to each channel. This is quite inconvenient with a multi-channel magnetic head.
To order the spin orientation in the MR element, the induced anisotropy caused by performing deposition of the thin film of the MR element within a magnetic field, or the shape anisotropy has hitherto been utilized. The latter is based on the effect where if the MR element has a rectangular shape the length l and the width w of which are in the relationship where 1/w&gt;l, the spin orientation tends to be ordered in the longitudinal direction of the element.
However satisfactory ordering of the spin oreintation has not been obtained by the above-mentioned method.